• Journal of Ocean Engineering and Technology
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• v.30 no.6
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• pp.526-534
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• 2016

This study had the goal of designing onboard structures for a pre-pilot mining test (PPMT), which is required for the commercialization of the deep-sea mining industry. This PPMT is planned to validate the performance of a hydraulic lifting system and verify the concept of operating through a moon-pool in the east sea, Korea. All of the onboard equipment and facility were designed by KRISO. Because the test was performed at the first development, it is difficult to determine what risk will occur in the facility. Therefore, risk-based design is required in the facility for the PPMT, which includes the facility layout, failure mode and effect analysis (FMEA), and risk reduction plan. All of the expected performances of the lifting system itself and the onboard facilities were qualitatively validated using the risk-based design.

• Journal of Korean Port Research
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• v.15 no.1
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• pp.37-46
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• 2001

Fuzzy logic control(FLC) is composed of three parts : fuzzy rule-bases, membership functions, and scaling factors. Well-defined fuzzy rule-base should contain proper physical intuition on the plant, so are needed lots of experiences of the skillful expert. When membership functions are considered, some parameters on the memberships function such as function shape, support, allocation density should be selected well. The rule of scaling factors is 'scaling'(amplifying or reducing) for both input and output signals of the FLC to fit in the membership function support and to operate the plant intentionally. To get a better performance of the FLC, it is necessary to adjust the parameters of the FLC. In general, the adaptation of the scaling factors is the most effective adjustment scheme, compared with that of the fuzzy rule-base or membership function parameters. This study proposes the adaptation scheme of the scaling factors. When the adaptation is performed on-line, the stability of the adaptive FLC should be guaranteed. The stable FLC system can be designed with stability analysis in the sense of Lyapunov stability. To adapt the scaling factors for the error signals, the concept of the conventional MRAC would be introduced into slightly modified form. A tracking accuracy of the control system would be enhanced by the modified shape and support of the membership function. The simulation is achieved on the pilot plant with the hydraulic steering control of a UCT(Unmanned Container Transporter) of which modeling dynamics have lots of severe uncertainties and modeling errors.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.6
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• pp.533-541
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• 2011

This paper studies modeling of Jeju 80kV HVDC system and its controller by using PSCAD/EMTDC program. Reduced ac network is applied to verify interaction between ac network and dc system. Design parameter is applied to the converter transformer, harmonic filter and dc transmisstion line to simulate dc system. HVDC controller is divided into a rectifier controller and a inverter controller according to the converter operating mode. The inverter controller is composed of current control, voltage control and extingtion angle control. The rectifier controller is composed of current control and voltage control. Both controller has VDCOL characteristics so that current order is dependant on voltage variation. Step response, ac network single phase fault, three phase fault is simulated to verify the dynamic performance of controller model in both transient state and steady state.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.251-254
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• 2007

Principal challenges to $\underline{direct\;fabrication}$ of high performance a-Si:H transistor arrays on flexible substrates include automated handling through bonding-debonding processes, substrate-compatible low temperature fabrication processes, management of dimensional instability of plastic substrates, and planarization and management of CTE mismatch for stainless steel foils. Viable solutions to address these challenges are described.

• Journal of the Korea Institute of Building Construction
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• v.20 no.1
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• pp.103-112
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• 2020

In Korea, local government officials are in charge of buildings, and as such are supposed to review submitted documents related to the architectural administration to ensure that they comply with the legal standards. However, these officials generally put a greater emphasis on the preparation of the set of documents required for the administrative work than the content the documents contain. For this reason, many experts point out that the shortage of officials specialized in buildings and construction, as well as the lack of expertise among the building officials in the local governments, may result in repeated safety accidents during building construction. The purpose of this study is to propose the operational direction of a Regional Building Safety (RBS) center to secure the performance and safety of buildings by utilizing private resources. In this study, we carried out a pilot project to verify the effects of an RBS center and to derive the specific number of experts required. As a result, the technical matters were resolved in approximately 15% of the total cases of the document processing procedure, and the level of technical specialization among the officers has also been improved through the provision of guidance. The research findings support the validity and effects of the introduction of the RBS center. Finally, this study proposes (1) the types of RBS Centers that should be established, (2) the roles and business scope of the RBS Center, (3) the specific number of experts required, (4) the qualifications of the experts, and (5) the business regulations of the RBS Center.

• Journal of Convergence for Information Technology
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• v.8 no.2
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• pp.203-208
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• 2018

This study is concerned with the introduction and operation of smart factories. In order to accomplish the purpose of research, we made a standard system of smart factory and investigated the recognition system. This study was conducted as a grounded theory methodology among qualitative research methodologies. The results of the study are the necessity of a tool to appropriately evaluate the new manufacturing process management system and related management activities to achieve the successful introduction of smart factories and the management performance of the organization. In order to successfully implement the Smart Factory Certification System, it is necessary to establish a certification organization system, enact relevant laws and amendments, operate government-led pilot projects, train professional workers, and establish incentive policies.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.45 no.6
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• pp.332-342
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• 2019

Objectives: Socket grafting is vital to prevent bone resorption after tooth extraction. Several techniques to prevent resorption have been described, and various bone graft substitutes have been developed and used with varying success. We conducted this pilot study to evaluate the performance of nanohydroxyapatite (nHA) derived from chicken eggshells in socket preservation. Materials and Methods: This was a prospective, single center, outcome assessor-blinded evaluation of 23 sockets (11 patients) grafted with nHA and covered with platelet-rich fibrin (PRF) membrane as a barrier. Bone width and radiographic bone density were measured using digital radiographs at 1, 12, and 24 weeks post-procedure. Postoperative histomorphometric and micro-computed tomography (CT) evaluation were performed. The study protocol was approved by the Institutional Ethics Committee. Results: All patients had uneventful wound healing without graft material displacement or leaching despite partial exposure of the grafted socket. Tissue re-epithelialized with thick gingival biotype (>3 mm). Width of the bone was maintained and radiographic density increased significantly with a trabecular pattern (73.91% of sockets) within 12 weeks. Histomorphometric analysis showed 56.52% Grade 3 bone formation and micro-CT analysis revealed newly formed bone with interconnecting trabeculae. Conclusion: Use of a PRF membrane with nHA resulted in good bone regeneration in sockets. Use of a PRF membrane prevents periosteal-releasing incisions for primary closure, thereby facilitating the preservation of keratinized mucosa and gingival architecture. This technique, which uses eggshell-derived nHA and PRF membrane from the patient's own blood, is innovative and is free of disease transfer risks. nHA is a promising economic bone graft substitute for bone regeneration and reconstruction because of the abundant availability of eggshell waste as a raw material.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.22 no.4
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• pp.211-218
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• 2011

Objectives : Intellectual impairment in children with attention-deficit hyperactivity disorder (ADHD) is often associated with relatively severe cognitive dysfunction. This study was designed to investigate cognitive function using auditory and visual event-related potential P300 in children with ADHD with relatively higher and lower IQ. Methods : A total of 20 children aged 6-12 years with DSM-IV-TR diagnosis of ADHD-combined type were recruited. For 10 children with lower IQ (${\leq}$100) and 10 children with higher IQ (>100), auditory and visual P300 using oddball paradigm (target 0.2, standard 0.8, in probability) were employed. Results : No significant differences were found in P300 amplitude and latency between ADHD children with higher and lower IQ in both modalities. However, auditory P300 amplitude in the right parietal area (P8 electrode) was negatively correlated with verbal IQ in ADHD subjects (R=-.50, p<.05). Visual P300 amplitude in the left parietal area (P3 electrode) was positively correlated with performance IQ in ADHD subjects (R=.57, p<.01). Conclusion : This study suggests intellectual impairment, as evidenced by lower IQ, could not be associated with cognitive dysfunction reflected in event-related potential P300 in ADHD children. However, cognitive function reflected in intellectual subcomponents and P300 might be processed in a stimulus modality-specific and asymmetric pattern.

• Membrane and Water Treatment
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• v.6 no.1
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• pp.77-94
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• 2015

Ultrafiltration membranes have several advantages over conventional drinking-water treatment. However, this technology presents major limitations, such as irreversible fouling and low removal of natural organic matter. Fouling depends heavily on the raw-water quality as well as on the operating conditions of the process, including flux, permeate recovery, pre-treatment, chemical cleaning, and backwashing. Starting with the premise that the optimisation of operating variables can improve membrane performance, different experiments were conducted in a pilot plant located in Granada (Spain). Several combinations of permeate and backwashing flow rates, backwashing frequencies, and aeration flow rates were tested for low-quality water coming from Genil River with the following results: the effluent quality did not depend on the combination of operating conditions chosen; and the membrane was effective for the removal of microorganisms, turbidity and suspended solids but the yields for the removal of dissolved organic carbon were extremely low. In addition, the threshold transmembrane pressure (-0.7 bar) was reached within a few hours and it was difficult to recover due to the low efficiency of the chemical cleanings. Moreover, greater transmembrane pressure due to fouling also increased the energy consumption, and it was not possible to lower it without compromising the permeate recovery. Finally, the intensification of aeration contributed positively to lengthening the operation times but again raised energy consumption. In light of these findings, the feasibility of ultrafiltration as a single treatment is questioned for low-quality influents.

• Journal of Wetlands Research
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• v.11 no.2
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• pp.55-66
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• 2009

The increase of pollutant loadings from nonpoint sources affect the water quality of the major rivers in Korea. Consequently, the need for managing the nonpoint source (NPS) pollution becomes the main concern of the Korean Ministry of Environment (MOE). Recently, the policy was changed from pollutant concentration-restricting approach to the total maximum daily load (TMDL) approach to improve the water quality and protect the aquatic ecosystem. Part of the program is the construction of Best Management Practice (BMP) pilot facilities basically to control NPS. Most of the BMPs adopted were foreign technologies which could not be properly employed in the country due to some limitations such as climate, watershed characteristics, etc. In other words, to be able to apply the BMPs, research on its applicability is necessary. In this study, a three-year monitoring has been conducted to assess the treatment performance of the BMP installed in highway toll plaza and parking lot. The data gathered aid in the characterization of NPS pollutants in runoff and estimation of the pollutant removal efficiency of the BMP. The results will be used for the future implementation of BMP in different land uses as well as for the determination of optimum operation and maintenance.